Several packaging materials have been designed and applied for the transportation and disposal or analysis of aqueous samples including body fluids such as urine, plasma and blood. These packages can be of various shapes, sizes and forms, such as cylindrical, spherical, pouch-like or carton-like, and typically consist of a sealable, multi-layered container with a central layer consisting of cross-linked ionized and/or ionizable polymers. Examples of such polymers include sodium polyacrylate based formulations like (C3H3O2Na)n and variations thereof such as those described in U.S. Pat. Nos. 6,161,687 and 5,984,087. Surrounding the central layer is: (i) an outer layer made of a material which is non-permeable to liquids, including certain types of paper, cardboard, wood or polymer laminate based on thermoplastic resins, vinyl polymers, polyolefins or polyesters, and (ii) an inner layer made of water permeable or water-soluble compounds such as starch paper, cellulose-based films or other water-soluble synthetic films.
When a liquid enclosed within such a multi-layered package leaks inside the container, it passes through the inner water-soluble layer and is absorbed by the absorbent material (the cross-linked polymer). This results in the formation of a liquid-swollen absorbent gel. The ability of the absorbent material to swell with the liquid and to form a gel has applications including, but not limited to, the containment and immobilization of a liquid spill. When the fluid sample in the gel is unique or precious, as may happen during the transport and testing of blood or DNA samples required for criminal investigations, DWI cases, drug abuse tests related to athletic events, regular workplace check-ups and the like, the containment alone of spilled samples is insufficient. In such cases, the recovery of the sample fluid and its subsequent testing is critical.
Thus, in the field of packaging materials, there is a need for a methodology to recover liquids such as biological samples spilled into the packaging materials.